The recent Haiti earthquake relief effort was yet another example of how a large military force, organized and trained to deal with chaotic situations, is often best prepared for handling major natural disasters. Over 20,000 American troops were sent to Haiti, along with dozens of ships and air transports, to deal with the chaotic situation there (200,000 dead, 500,000 injured, two million homeless). UAVs and satellites provided accurate pictures of the damage, and specialized aircraft like the EC-130 Commando Solo (flying TV and radio broadcasting station for psychological warfare), restored AM and FM radio broadcasts (essential to let people know what emergency services were available, and where.) The navy sent a hospital ship, plus several aircraft carriers and amphibious ships (each carrying a dozen or more helicopters). Armed soldiers and marines went ashore and restored order in areas where armed gangs were looting and threatening earthquake survivors. Military engineers quickly reopened the wrecked port and got large quantities of ship delivered cargo moving in. No one else could have done so much, in such a short time.
The Haiti situation was not unique, and military techniques are changing the way civilian relief organizations do their work as well. Peacekeeping often involves a lot of disaster relief, and that usually means a lot of civilians working alongside the troops, or by themselves, to do it. Civilians doing disaster relief are increasingly using military equipment, not just because it's well suited to the job, but because it enables them to work more effectively with the soldiers. Peacekeeping is what it is because there are still unpredictable gunmen in the area, as well as a lot of civilians in desperate need.
In the past, civilian disaster relief workers generally had better gear than the military, because the main source for the civilian relief workers was the commercial market, which moved faster with innovations than the military. However, in the past decade or so, that has changed. The major source of that change has been the U.S. military, which has been increasingly rapid in its adoption of civilian gear and, more importantly, improving and adapting it for military purposes. This has encouraged civilian firms to develop new items for military use, knowing that it was more likely that the military would buy the new gear. For example, a GPS guided parachute system was developed, to provide accurate drops of military equipment. The military quickly bought this one, but the system is also very useful for disaster relief, and even some commercial applications.
Communications systems are one area where new military systems and concepts are directly transferable to civilian use. The military has done a lot of take widely used computer networking technology, make it more robust (physically and performance wise) and create a system that can be quickly set up anywhere, like in the middle of a disaster area. The military did this in the wake of hurricane Katrina. Civilian disaster relief organizations took note, and similar systems showed up in Haiti.
Military medicine is also well adapted to a "disaster" situation, as are many of the tools the military uses to move around and survive in rough neighborhoods. The military has long taken the lead in developing water purification systems. Bad water is a major cause of disease in disaster zones. The military also knows how to preserve supplies that are being temporarily stored in desolate areas, or stored for longer periods "just-in-case" ("pre-positioned equipment.") The United States has developed a special civilian version of their MRE field rations, specifically for disaster relief (like feeding civilian refugees in a combat zone.)
The U.S. Department of Defense has noticed all this, and has put more resources and effort into disaster relief. Part of the reason is that the American military is often called on to do this sort of work. There's also the PR angle, U.S. troops helping out in non-military disasters is good for the image. But civilian disaster relief organizations are finding out that there's a lot of useful equipment and ideas behind the image, stuff that is well worth adopting.
Cuba and Venezuela are, for propaganda purposes, calling the use of American troops for disaster relief in Haiti, a cover for an invasion of the country. There are thousands of U.S. troops in Haiti, but they are mostly unarmed, and passing food and medical supplies, not ammunition.